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Tregoning, R.*; Wallace, J.*; Bouydo, A.*; Costa-Garrido, O.*; Dillstr
m, P.*; Duan, X.*; Heckmann, K.*; Kim, Y.-B.*; Kim, Y.*; Kurth-Twombly, E.*; et al.
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 11 Pages, 2022/07
Fourteen organizations, representing eleven countries, participated in a leak-before-break (LBB) benchmark exercise that compared results from analyses among participating countries and identified the effects of weld residual stress (WRS) and crack morphology on crack opening displacement (COD), critical bending moment (CBM), and leak rate (LR) results. The participants determined whether the initial problem would meet their country's LBB acceptance criteria and then evaluated the effects of crack morphology and WRS for a prescribed crack size, geometry and loading. Six out of fourteen participants indicated that the initial problem met their LBB requirements. In the follow-on tasks, differences among the participant's CBM predictions were principally due to the material properties used in the analysis while the type of failure model chosen contributed much less. Most of the differences in the LR predictions were directly attributable to differences among the COD models, but a portion was attributable to the treatment of crack face pressure (CFP). The benchmark identified several aspects of an LBB analysis that could support a more realistic evaluation.
Kang, Z.; Okuda, Yukihiko; Nishida, Akemi; Tsubota, Haruji; Li, Y.
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 8 Pages, 2022/07
So far, studies on local damage to reinforced concrete (RC) panels subjected to projectile impact have mainly focused on collisions that occur at an angle normal to the structure, while research on oblique impact is scarce. In this research, we conducted a series of impact tests to confirm validity of the analytical method based on the investigation on local damage behavior of RC panel due to projectile impact under various impact conditions covering impact angles, projectile types (rigid and soft) and RC panel's thickness. In part 2, we concentrate on the investigation to the penetration damage and scabbing damage of RC panels subjected to normal and oblique impact by rigid and soft projectiles. Based on the analysis of experimental results, the obtained knowledge will be presented.
Futagami, Satoshi; Ando, Masanori; Yamano, Hidemasa
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 9 Pages, 2022/07
Okuda, Yukihiko; Kang, Z.; Nishida, Akemi; Tsubota, Haruji; Li, Y.
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 10 Pages, 2022/07
When a projectile collides with a nuclear building, stress waves are generated at the impacted area and propagate to the interior of the building through the building structure. Assessing the influence of dynamic responses generated by the projectile impact on internal equipment is important, because stress waves are likely to excite high-frequency vibrations of the internal equipment and may influence the functionality of the internal equipment. Therefore, we performed a projectile impact test on a reinforced concrete (RC) structure that models a nuclear building with internal equipment. This paper presents the results of the investigation of the impact response characteristics of the RC structure subjected to projectile impact.
Choi, B.; Nishida, Akemi; Shiomi, Tadahiko; Kawata, Manabu; Li, Y.
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 10 Pages, 2022/07
In order to improve the seismic probabilistic risk assessment method, the authors are developing methods related to realistic response, realistic resistance and fragility assessment for buildings and equipment that are important for seismic safety. In this study, in order to identify of building damage mode subjected to large seismic motions, pushover analyses using multiple analysis codes were performed using a 3D FE model of a reactor building. We obtained the analysis results for the identification of local damage mode that contributes to the fragility assessment. In this paper, we report the progress of local damage mode and ultimate strength of the building by the pushover analysis. We also compared this result with the seismic response analysis results.
Nishida, Akemi; Kawata, Manabu; Choi, B.; Iigaki, Kazuhiko; Li, Y.
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 10 Pages, 2022/07
We have conducted research and development with the aim of improving the accuracy of three-dimensional seismic evaluation analysis method for nuclear buildings that contributes to probabilistic risk assessment caused by earthquakes (seismic PRA). In 2019, we started our research on improving the accuracy and validating the three-dimensional seismic analysis method used for nuclear buildings using actual seismic observation records in collaboration with the Nuclear Regulation Authority. In this research, we constructed a large-scale observation system that enabled simultaneous observation at multiple positions during natural earthquakes or artificial waves by installing accelerometers not only on/in the soil and on the floors of the building but also on the walls of the building, targeting the High Temperature engineering Test Reactor, which is one of nuclear facilities of JAEA. In this paper, we report the outline of the large-scale observation system and the knowledge obtained from the analysis results of the seismic observation records acquired using this system.
Nishida, Akemi; Murakami, Takahiro*; Satoda, Akira*; Asano, Yuya*; Guo, Z. H.*; Oshima, Masami*; Matsukawa, Keisuke*; Nakajima, Norihiro
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 10 Pages, 2022/07
no abstracts in English
Ichihara, Yoshitaka*; Nakamura, Naohiro*; Nabeshima, Kunihiko*; Choi, B.; Nishida, Akemi
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 10 Pages, 2022/07
The objective of this study is to evaluate the applicability of the equivalent linear analysis method for reinforced concrete, which uses frequency-independent complex damping with a small computational load, to the seismic design of reactor building of the nuclear power plant. To achieve this, the three-dimensional finite element analyses of the soil-structure interaction system focusing on the nonlinear and equivalent linear seismic behavior under an ideal soil condition were performed for Kashiwazaki-Kariwa nuclear power plant Unit 7 reactor building. From these results, the equivalent linear analysis method showed a generally good correspondence with the nonlinear analysis method, and the effectiveness of the method was confirmed.
Yamano, Hidemasa; Okamura, Shigeki*
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 9 Pages, 2022/07
Seismic response analyses were conducted for the pipe with and without the seismic isolation system based on the response waveforms. This study performed a fragility analysis by setting uncertainty parameters on the basis of existing studies. The comparison results showed that the seismic isolation technology is effective for the pipe to prevent cliff-edge effects. In other words, the seismic margin for the seismically isolated plant is 1.2 times larger than that of the non-isolated plant. To evaluate the response reduction effect, this study focused on response coefficients of components as uncertainty parameters, which were specified within a physically possible range. Even if the uncertainty is considered, the HCLPF for the isolated plant is nearly twice as high as the non-isolated plant, namely the response reduction effect is still significant for the isolated plant. Therefore, the isolation technology is effective to avoid cliff-edge effects.
Kasahara, Naoto*; Yamano, Hidemasa; Nakamura, Izumi*; Demachi, Kazuyuki*; Sato, Takuya*; Ichimiya, Masakazu*
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 8 Pages, 2022/07
Utilizing fracture control, we are developing a technology to suppress the expansion of damage caused by an event that exceeds the design assumption. We made a plan to develop three issues; (1) Technology for mitigating failure consequence at extremely high temperatures, (2) Technology for mitigating failure consequence against excessive earthquakes, and (3) Methodology for improving reactor structure resilience.
Kinoshita, Takahiro*; Okamura, Shigeki*; Nishino, Hiroyuki; Yamano, Hidemasa; Kurisaka, Kenichi; Futagami, Satoshi; Fukasawa, Tsuyoshi*
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 7 Pages, 2022/07
The seismic evaluation of key components such as reactor vessel is important for the Seismic Probabilistic Risk Assessment (S-PRA) in a Sodium-Cooled Fast Reactor (SFR). Many components were damaged by cumulative damage like fatigue damage during seismic ground motion. However, general evaluation method for key components under seismic ground motion has been based on static loads and elastic region of materials. More accurate evaluation method for S-PRA, which can evaluate the failure of key components such as reactor vessels, has been actually required. In this study, failure probability evaluation method with integrated energy was developed by comparing the energy with vibration tests and fatigue tests. Vibration tests were performed to evaluate integrated vibration energy at failure by energy balance equation and fatigue tests were performed to evaluate integrated vibration energy at failure based on experimental results of fatigue tests.